A "substantial reward" has been offered after heirlooms, including a ring given by Charles II to a mistress, were stolen from a stately home.
A tiara and more than 40 diamond, sapphire and emerald items were stolen during a break-in at Goodwood House, West Sussex, on 13 January.
The jewellery belonging to Lord and Lady March is said to be irreplaceable.
Police have not given a figure for the reward being offered in return for information about the missing items.
Jewellery stolen from Goodwood House
1820 diamond tiara worth £400,000
- Diamond necklace from the first half of the 19th Century worth £200,000
- Emerald and diamond ring engraved with Duchess's coronet and monogram CL for Louise de Keroualle, Duchess of Portsmouth, the mistress of Charles II
- Antique Rolex and Girard Perregaux watches
Det Insp Till Sanderson, of Sussex Police, said his team had been working closely with Lord and Lady March and the estate to trace and identify the people responsible for the theft of this "treasured property".
"I hope the offer of a substantial reward by the insurers, for information leading to the recovery of important items of jewellery and personal effects of historical significance, will encourage anyone who knows anything to come forward," he added.
A 26-year-old man from Hampshire who was arrested in connection with the raid has been bailed until February.